First up, my review.
When the 2DS was first announced many of us thought it looked big, ugly, and a little unwieldy (you can see the original discussion here: http://cheerfulghost.com/WhiteboySlim/posts/1567). I'm happy to report that, although it's still a little ugly, it is much easier to hold to and play than I had originally thought. Having used an iPad before I would say I have a much easier time with the 2DS than I do the iPad. It definitely has a certain heft to it, but it's not too bad. The longest stretch of time I've gotten with it was between 1 and a half to two hours and I didn't really get tired of holding it. I don't own a 3DS, so I can't show you a comparison between the two. Here are a couple photos showing the 2DS next to a DS though:
Next to the DS (w/DS open): http://i.imgur.com/pFbyDWy.jpg
Next to the DS (w/DS closed): http://i.imgur.com/F19XIr2.jpg
As you can see, it's slightly smaller than the DS when open, but considerably larger than the DS when closed.
(On a side note, that is my daughter's gameboy, thus the bedazzled Princess Peach and blue crayon mark on the screen.)
My only real complaint about the system is that it is just slightly too big to really be that portable. I can't fit it into my pocket, which makes my chances of bumping into the people via Street pass pretty low. The one time I did take it out with me I stuck it in my wife's purse. :P
The buttons feel good and the control stick is light-years ahead of the one my PSP has even thought they're roughly the same design. And I say this as someone who actually really loved the PSP. Where the PSP control stick felt stiff the 2DS is nice and smooth but still snaps back into the neutral position when you want it to. It is also slightly textured and your thumb sticks to it nicely.
It's hard to comment on the screen because I only have one 3DS game so far (Pokemon Y) and the graphics on it are pretty cartoony. But for what it's worth Pokemon looks really, really good.
Over all I really enjoy my 2DS. It's turned out to be a much better system than I was originally expecting and I'm looking forward to expanding my game library and spending more time with it.
Speaking of which... I need some suggestions on what games to get! As I mentioned before I currently have Pokemon Y and I've ordered Fire Emblem Awakening on Amazon but have yet to receive it. Leave your suggestions in the comments! (I'm mostly interested in 3DS games but feel free to suggest some stellar DS games too!)